Edinburgh Castle

What is it: There has been a royal castle on Castle Rock in Edinburgh since the reign of David I in the 12th century. It was a royal residence until 1633 after which it was mainly used as a military barracks. Castle Rock is actually the plug of an extinct volcano.
What's it like: The Lonely Planet says that it looks like it 'grew' from the rock and it really does - it's a true part of Edinburgh. 
Where: Edinburgh, Scotland 
When: March 2008 
How: We flew to Edinburgh for a weekend for the Scotland vs England rugby match. Pete subsequently refused to take me to any more rugby matches as I complained a bit. We also saw the Royal Mile (248). 
Worth noting: The One O'Clock Gun fires every day except Sundays, Good Friday, and Christmas Day. It originally let ships in the Firth of Forth know the time, although it did fire at a Zeppelin once in 1916, its one and only act of war. 

Place in the 2015 edition: 58
Did it deserve to lose its place in the 2020 top 500: Probably not.